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        </div><article class="page single"><h1 class="single-title animated flipInX">Spring源码 - RequestMappingHandlerMapping和RequestMappingHandlerAdapter初始化</h1><div class="post-meta">
            <div class="post-meta-line"><span class="post-author"><a href="https://wlizhi.cc" title="Author" target="_blank" rel="noopener noreffer author" class="author"><i class="fas fa-user-circle fa-fw"></i>Wlizhi</a></span>&nbsp;<span class="post-category">收录于 <a href="/categories/spring/"><i class="far fa-folder fa-fw"></i>spring</a></span></div>
            <div class="post-meta-line"><i class="far fa-calendar-alt fa-fw"></i>&nbsp;<time datetime="2020-12-16">2020-12-16</time>&nbsp;<i class="fas fa-pencil-alt fa-fw"></i>&nbsp;约 5317 字&nbsp;
                <i class="far fa-clock fa-fw"></i>&nbsp;预计阅读 11 分钟&nbsp;<span id="/posts/spring/25-request-mapping-and-adapter-init/" class="leancloud_visitors" data-flag-title="Spring源码 - RequestMappingHandlerMapping和RequestMappingHandlerAdapter初始化">
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  <ul>
    <li><a href="#1-requestmappinghandlermapping-的初始化">1 RequestMappingHandlerMapping 的初始化</a>
      <ul>
        <li><a href="#11-主要流程">1.1 主要流程</a></li>
        <li><a href="#12-获取-method-requestmappinginfo-映射">1.2 获取 Method-RequestMappingInfo 映射</a></li>
        <li><a href="#13-注册-handlermethod">1.3 注册 HandlerMethod</a></li>
      </ul>
    </li>
    <li><a href="#2-requestmappinghandleradapter-的初始化">2 RequestMappingHandlerAdapter 的初始化</a>
      <ul>
        <li><a href="#21-数据结构">2.1 数据结构</a></li>
        <li><a href="#22-主流程">2.2 主流程</a></li>
        <li><a href="#23-初始化-controlleradvice-缓存">2.3 初始化 ControllerAdvice 缓存</a></li>
        <li><a href="#24-注册默认参数解析器">2.4 注册默认参数解析器</a></li>
        <li><a href="#25-注册默认返回值处理类">2.5 注册默认返回值处理类</a></li>
      </ul>
    </li>
  </ul>
</nav></div>
            </div><div class="content" id="content"><p>spring源码系列文章，示例代码的中文注释，均是 copy 自 <a href="https://gitee.com/wlizhi/spring-framework" target="_blank" rel="noopener noreffer">https://gitee.com/wlizhi/spring-framework</a> 。</p>
<p>链接中源码是作者从 github 下载，并以自身理解对核心流程及主要节点做了详细的中文注释。</p>
<hr>
<p>在@EnableWebMvc注解，激活mvc的一些组件时，其中就创建了 RequestMappingHandlerMapping 和 RequestMappingHandlerAdapter。</p>
<p>这两个类本身也是 InitializingBean 的实现，所以在创建后会调用 afterPropertiesSet() 初始化。</p>
<h2 id="1-requestmappinghandlermapping-的初始化">1 RequestMappingHandlerMapping 的初始化</h2>
<p>RequestMappingHandlerMapping 主要封装 url、方法上的 @RequestMapping 注解信息、HandlerMethod、跨域配置等的一些映射关系，以及提供与此相关的一些操作方法。</p>
<h3 id="11-主要流程">1.1 主要流程</h3>
<p>方法调用流程：</p>
<blockquote>
<p>afterPropertiesSet() -&gt; super.afterPropertiesSet() -&gt; initHandlerMethods() -&gt; processCandidateBean() -&gt; detectHandlerMethods()</p>
</blockquote>
<p>initHandlerMethods() 源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">abstract</span> <span class="kd">class</span> <span class="nc">AbstractHandlerMethodMapping</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMapping</span> <span class="kd">implements</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="kd">protected</span> <span class="kt">void</span> <span class="nf">initHandlerMethods</span><span class="o">()</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 获取ApplicationContext容器中所有的beanName，循环判断不是以scopedTarget.开头的beanName执行候选操作。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">for</span> <span class="o">(</span><span class="n">String</span> <span class="n">beanName</span> <span class="o">:</span> <span class="n">getCandidateBeanNames</span><span class="o">())</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(!</span><span class="n">beanName</span><span class="o">.</span><span class="na">startsWith</span><span class="o">(</span><span class="n">SCOPED_TARGET_NAME_PREFIX</span><span class="o">))</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="c1">// TODO 执行操作。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="n">processCandidateBean</span><span class="o">(</span><span class="n">beanName</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 一个钩子方法，在查找并封装完完所有的处理方法各种映射关系之后，进行调用。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">handlerMethodsInitialized</span><span class="o">(</span><span class="n">getHandlerMethods</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>首先从容器中获取所有的 beanName 的数组。</p>
<p>遍历这些 beanName，将其作为参数依次调用 processCandidateBean()。</p>
<p>detectHandlerMethods() 源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">abstract</span> <span class="kd">class</span> <span class="nc">AbstractHandlerMethodMapping</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMapping</span> <span class="kd">implements</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="kd">protected</span> <span class="kt">void</span> <span class="nf">detectHandlerMethods</span><span class="o">(</span><span class="n">Object</span> <span class="n">handler</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">handlerType</span> <span class="o">=</span> <span class="o">(</span><span class="n">handler</span> <span class="k">instanceof</span> <span class="n">String</span> <span class="o">?</span>
</span></span><span class="line"><span class="cl">				<span class="n">obtainApplicationContext</span><span class="o">().</span><span class="na">getType</span><span class="o">((</span><span class="n">String</span><span class="o">)</span> <span class="n">handler</span><span class="o">)</span> <span class="o">:</span> <span class="n">handler</span><span class="o">.</span><span class="na">getClass</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="n">handlerType</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">userType</span> <span class="o">=</span> <span class="n">ClassUtils</span><span class="o">.</span><span class="na">getUserClass</span><span class="o">(</span><span class="n">handlerType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// 获取方法 - RequestMappingInfo 的映射
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">Map</span><span class="o">&lt;</span><span class="n">Method</span><span class="o">,</span> <span class="n">T</span><span class="o">&gt;</span> <span class="n">methods</span> <span class="o">=</span> <span class="n">MethodIntrospector</span><span class="o">.</span><span class="na">selectMethods</span><span class="o">(</span><span class="n">userType</span><span class="o">,</span>
</span></span><span class="line"><span class="cl">					<span class="o">(</span><span class="n">MethodIntrospector</span><span class="o">.</span><span class="na">MetadataLookup</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;)</span> <span class="n">method</span> <span class="o">-&gt;</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">						<span class="k">try</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">							<span class="c1">// 根据类和方法上RequestMapping中的value，结合成一个路径封装成RequestMappingInfo返回
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>							<span class="k">return</span> <span class="n">getMappingForMethod</span><span class="o">(</span><span class="n">method</span><span class="o">,</span> <span class="n">userType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">						<span class="o">}</span>
</span></span><span class="line"><span class="cl">						<span class="k">catch</span> <span class="o">(</span><span class="n">Throwable</span> <span class="n">ex</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">							<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">&#34;Invalid mapping on handler class [&#34;</span> <span class="o">+</span>
</span></span><span class="line"><span class="cl">									<span class="n">userType</span><span class="o">.</span><span class="na">getName</span><span class="o">()</span> <span class="o">+</span> <span class="s">&#34;]: &#34;</span> <span class="o">+</span> <span class="n">method</span><span class="o">,</span> <span class="n">ex</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">						<span class="o">}</span>
</span></span><span class="line"><span class="cl">					<span class="o">});</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(</span><span class="n">logger</span><span class="o">.</span><span class="na">isTraceEnabled</span><span class="o">())</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="n">logger</span><span class="o">.</span><span class="na">trace</span><span class="o">(</span><span class="n">formatMappings</span><span class="o">(</span><span class="n">userType</span><span class="o">,</span> <span class="n">methods</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// TODO 注册处理方法
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">methods</span><span class="o">.</span><span class="na">forEach</span><span class="o">((</span><span class="n">method</span><span class="o">,</span> <span class="n">mapping</span><span class="o">)</span> <span class="o">-&gt;</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="c1">// 获取到可调用的方法
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="n">Method</span> <span class="n">invocableMethod</span> <span class="o">=</span> <span class="n">AopUtils</span><span class="o">.</span><span class="na">selectInvocableMethod</span><span class="o">(</span><span class="n">method</span><span class="o">,</span> <span class="n">userType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">				<span class="c1">// TODO 注册 HandlerMethod
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="n">registerHandlerMethod</span><span class="o">(</span><span class="n">handler</span><span class="o">,</span> <span class="n">invocableMethod</span><span class="o">,</span> <span class="n">mapping</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">});</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><ol>
<li>遍历类中所有方法，获取 Method - RequestMappingInfo 的映射关系。</li>
<li>注册 HandlerMethod。</li>
</ol>
<h3 id="12-获取-method-requestmappinginfo-映射">1.2 获取 Method-RequestMappingInfo 映射</h3>
<p>selectMethods() 源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">final</span> <span class="kd">class</span> <span class="nc">MethodIntrospector</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">	<span class="kd">public</span> <span class="kd">static</span> <span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="n">Map</span><span class="o">&lt;</span><span class="n">Method</span><span class="o">,</span> <span class="n">T</span><span class="o">&gt;</span> <span class="nf">selectMethods</span><span class="o">(</span><span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">targetType</span><span class="o">,</span> <span class="kd">final</span> <span class="n">MetadataLookup</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="n">metadataLookup</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="kd">final</span> <span class="n">Map</span><span class="o">&lt;</span><span class="n">Method</span><span class="o">,</span> <span class="n">T</span><span class="o">&gt;</span> <span class="n">methodMap</span> <span class="o">=</span> <span class="k">new</span> <span class="n">LinkedHashMap</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">		<span class="n">Set</span><span class="o">&lt;</span><span class="n">Class</span><span class="o">&lt;?&gt;&gt;</span> <span class="n">handlerTypes</span> <span class="o">=</span> <span class="k">new</span> <span class="n">LinkedHashSet</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">		<span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">specificHandlerType</span> <span class="o">=</span> <span class="kc">null</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(!</span><span class="n">Proxy</span><span class="o">.</span><span class="na">isProxyClass</span><span class="o">(</span><span class="n">targetType</span><span class="o">))</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">specificHandlerType</span> <span class="o">=</span> <span class="n">ClassUtils</span><span class="o">.</span><span class="na">getUserClass</span><span class="o">(</span><span class="n">targetType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="n">handlerTypes</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="n">specificHandlerType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 获取类实现的所有接口
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">handlerTypes</span><span class="o">.</span><span class="na">addAll</span><span class="o">(</span><span class="n">ClassUtils</span><span class="o">.</span><span class="na">getAllInterfacesForClassAsSet</span><span class="o">(</span><span class="n">targetType</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">for</span> <span class="o">(</span><span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">currentHandlerType</span> <span class="o">:</span> <span class="n">handlerTypes</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="kd">final</span> <span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">targetClass</span> <span class="o">=</span> <span class="o">(</span><span class="n">specificHandlerType</span> <span class="o">!=</span> <span class="kc">null</span> <span class="o">?</span> <span class="n">specificHandlerType</span> <span class="o">:</span> <span class="n">currentHandlerType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">			<span class="n">ReflectionUtils</span><span class="o">.</span><span class="na">doWithMethods</span><span class="o">(</span><span class="n">currentHandlerType</span><span class="o">,</span> <span class="n">method</span> <span class="o">-&gt;</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="n">Method</span> <span class="n">specificMethod</span> <span class="o">=</span> <span class="n">ClassUtils</span><span class="o">.</span><span class="na">getMostSpecificMethod</span><span class="o">(</span><span class="n">method</span><span class="o">,</span> <span class="n">targetClass</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">				<span class="n">T</span> <span class="n">result</span> <span class="o">=</span> <span class="n">metadataLookup</span><span class="o">.</span><span class="na">inspect</span><span class="o">(</span><span class="n">specificMethod</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span> <span class="o">(</span><span class="n">result</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">					<span class="n">Method</span> <span class="n">bridgedMethod</span> <span class="o">=</span> <span class="n">BridgeMethodResolver</span><span class="o">.</span><span class="na">findBridgedMethod</span><span class="o">(</span><span class="n">specificMethod</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">					<span class="c1">// inspect() 调用到了外层的匿名对象
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>					<span class="k">if</span> <span class="o">(</span><span class="n">bridgedMethod</span> <span class="o">==</span> <span class="n">specificMethod</span> <span class="o">||</span> <span class="n">metadataLookup</span><span class="o">.</span><span class="na">inspect</span><span class="o">(</span><span class="n">bridgedMethod</span><span class="o">)</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">						<span class="c1">// 方法-RequestMappingInfo映射
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>						<span class="n">methodMap</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">specificMethod</span><span class="o">,</span> <span class="n">result</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">					<span class="o">}</span>
</span></span><span class="line"><span class="cl">				<span class="o">}</span>
</span></span><span class="line"><span class="cl">			<span class="o">},</span> <span class="n">ReflectionUtils</span><span class="o">.</span><span class="na">USER_DECLARED_METHODS</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">return</span> <span class="n">methodMap</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><ol>
<li>遍历本类以及所有实现接口的 Class 对象。</li>
<li>获取到该 Class 中定义的所有方法、遍历。</li>
<li>调用外层匿名对象中的 inspect 方法，获取到 result，即会调用到 getMappingForMethod()，最终获取到 RequestMappingInfo 实例。</li>
<li>将当前方法与获取到的 RequestMappingInfo，建立映射管理，存储到一个 map 集合中。</li>
</ol>
<p>getMappingForMethod() 中，调用了 createRequestMappingInfo()，源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">RequestMappingHandlerMapping</span> <span class="kd">extends</span> <span class="n">RequestMappingInfoHandlerMapping</span>
</span></span><span class="line"><span class="cl">		<span class="kd">implements</span> <span class="n">MatchableHandlerMapping</span><span class="o">,</span> <span class="n">EmbeddedValueResolverAware</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">    <span class="c1">// 步骤 1
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="kd">protected</span> <span class="n">RequestMappingInfo</span> <span class="nf">getMappingForMethod</span><span class="o">(</span><span class="n">Method</span> <span class="n">method</span><span class="o">,</span> <span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">handlerType</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="n">RequestMappingInfo</span> <span class="n">info</span> <span class="o">=</span> <span class="n">createRequestMappingInfo</span><span class="o">(</span><span class="n">method</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="n">info</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// TODO 创建 RequestMappingInfo，这里完成了 @RequestMappingInfo 的扫描及封装操作。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">RequestMappingInfo</span> <span class="n">typeInfo</span> <span class="o">=</span> <span class="n">createRequestMappingInfo</span><span class="o">(</span><span class="n">handlerType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(</span><span class="n">typeInfo</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="c1">// 将类上的 @RequestMappingInfo 和方法上的 @RequestMappingInfo 结合。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="n">info</span> <span class="o">=</span> <span class="n">typeInfo</span><span class="o">.</span><span class="na">combine</span><span class="o">(</span><span class="n">info</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">			<span class="n">String</span> <span class="n">prefix</span> <span class="o">=</span> <span class="n">getPathPrefix</span><span class="o">(</span><span class="n">handlerType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(</span><span class="n">prefix</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="n">info</span> <span class="o">=</span> <span class="n">RequestMappingInfo</span><span class="o">.</span><span class="na">paths</span><span class="o">(</span><span class="n">prefix</span><span class="o">).</span><span class="na">build</span><span class="o">().</span><span class="na">combine</span><span class="o">(</span><span class="n">info</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="k">return</span> <span class="n">info</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="c1">// 步骤 2
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>	<span class="kd">private</span> <span class="n">RequestMappingInfo</span> <span class="nf">createRequestMappingInfo</span><span class="o">(</span><span class="n">AnnotatedElement</span> <span class="n">element</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 扫描 @RequestMapping 注解，将必要的信息封装成 RequestMappingInfo
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">RequestMapping</span> <span class="n">requestMapping</span> <span class="o">=</span> <span class="n">AnnotatedElementUtils</span><span class="o">.</span><span class="na">findMergedAnnotation</span><span class="o">(</span><span class="n">element</span><span class="o">,</span> <span class="n">RequestMapping</span><span class="o">.</span><span class="na">class</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="n">RequestCondition</span><span class="o">&lt;?&gt;</span> <span class="n">condition</span> <span class="o">=</span> <span class="o">(</span><span class="n">element</span> <span class="k">instanceof</span> <span class="n">Class</span> <span class="o">?</span>
</span></span><span class="line"><span class="cl">				<span class="n">getCustomTypeCondition</span><span class="o">((</span><span class="n">Class</span><span class="o">&lt;?&gt;)</span> <span class="n">element</span><span class="o">)</span> <span class="o">:</span> <span class="n">getCustomMethodCondition</span><span class="o">((</span><span class="n">Method</span><span class="o">)</span> <span class="n">element</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="k">return</span> <span class="o">(</span><span class="n">requestMapping</span> <span class="o">!=</span> <span class="kc">null</span> <span class="o">?</span> <span class="n">createRequestMappingInfo</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">,</span> <span class="n">condition</span><span class="o">)</span> <span class="o">:</span> <span class="kc">null</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="c1">// 步骤 3
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="kd">protected</span> <span class="n">RequestMappingInfo</span> <span class="nf">createRequestMappingInfo</span><span class="o">(</span>
</span></span><span class="line"><span class="cl">			<span class="n">RequestMapping</span> <span class="n">requestMapping</span><span class="o">,</span> <span class="nd">@Nullable</span> <span class="n">RequestCondition</span><span class="o">&lt;?&gt;</span> <span class="n">customCondition</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 这里面封装了方法上 @RequestMapping 注解的一些参数值。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">RequestMappingInfo</span><span class="o">.</span><span class="na">Builder</span> <span class="n">builder</span> <span class="o">=</span> <span class="n">RequestMappingInfo</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">paths</span><span class="o">(</span><span class="n">resolveEmbeddedValuesInPatterns</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">.</span><span class="na">path</span><span class="o">()))</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">methods</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">.</span><span class="na">method</span><span class="o">())</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">params</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">.</span><span class="na">params</span><span class="o">())</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">headers</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">.</span><span class="na">headers</span><span class="o">())</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">consumes</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">.</span><span class="na">consumes</span><span class="o">())</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">produces</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">.</span><span class="na">produces</span><span class="o">())</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">mappingName</span><span class="o">(</span><span class="n">requestMapping</span><span class="o">.</span><span class="na">name</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="n">customCondition</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">builder</span><span class="o">.</span><span class="na">customCondition</span><span class="o">(</span><span class="n">customCondition</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="k">return</span> <span class="n">builder</span><span class="o">.</span><span class="na">options</span><span class="o">(</span><span class="k">this</span><span class="o">.</span><span class="na">config</span><span class="o">).</span><span class="na">build</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>如果方法上有注解 @RequestMapping，则封装成 RequestMappingInfo。内部封装了方法、以及 @RequestMapping 中设置的一系列参数值。</p>
<h3 id="13-注册-handlermethod">1.3 注册 HandlerMethod</h3>
<p>在获取到 <code>方法 - RequestMappingInfo</code> 映射关系后，循环这个map，依次对其进行注册。</p>
<p>源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">abstract</span> <span class="kd">class</span> <span class="nc">AbstractHandlerMethodMapping</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMapping</span> <span class="kd">implements</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">	<span class="kd">protected</span> <span class="kt">void</span> <span class="nf">registerHandlerMethod</span><span class="o">(</span><span class="n">Object</span> <span class="n">handler</span><span class="o">,</span> <span class="n">Method</span> <span class="n">method</span><span class="o">,</span> <span class="n">T</span> <span class="n">mapping</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// TODO 注册映射信息
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">this</span><span class="o">.</span><span class="na">mappingRegistry</span><span class="o">.</span><span class="na">register</span><span class="o">(</span><span class="n">mapping</span><span class="o">,</span> <span class="n">handler</span><span class="o">,</span> <span class="n">method</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>register() 源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">abstract</span> <span class="kd">class</span> <span class="nc">AbstractHandlerMethodMapping</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMapping</span> <span class="kd">implements</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="kd">public</span> <span class="kt">void</span> <span class="nf">register</span><span class="o">(</span><span class="n">T</span> <span class="n">mapping</span><span class="o">,</span> <span class="n">Object</span> <span class="n">handler</span><span class="o">,</span> <span class="n">Method</span> <span class="n">method</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">        <span class="k">this</span><span class="o">.</span><span class="na">readWriteLock</span><span class="o">.</span><span class="na">writeLock</span><span class="o">().</span><span class="na">lock</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">        <span class="k">try</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">            <span class="c1">// 封装HanlderMethod
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="n">HandlerMethod</span> <span class="n">handlerMethod</span> <span class="o">=</span> <span class="n">createHandlerMethod</span><span class="o">(</span><span class="n">handler</span><span class="o">,</span> <span class="n">method</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="n">assertUniqueMethodMapping</span><span class="o">(</span><span class="n">handlerMethod</span><span class="o">,</span> <span class="n">mapping</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="c1">// TODO 封装 RequestMappingInfo - HandlerMethod 映射关系
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="k">this</span><span class="o">.</span><span class="na">mappingLookup</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">mapping</span><span class="o">,</span> <span class="n">handlerMethod</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="c1">// url - mapping 映射关系，mapping-handlerMethod的映射关系。这两个map很重要。请求url匹配到处理方法，就是通过这两个关系映射来匹配的。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="c1">// TODO 获取到RequestMappingInfo中的 paths（用于匹配请求路径的url），遍历，依次建立 url - RequestMappingInfo的映射关系。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="n">List</span><span class="o">&lt;</span><span class="n">String</span><span class="o">&gt;</span> <span class="n">directUrls</span> <span class="o">=</span> <span class="n">getDirectUrls</span><span class="o">(</span><span class="n">mapping</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="k">for</span> <span class="o">(</span><span class="n">String</span> <span class="n">url</span> <span class="o">:</span> <span class="n">directUrls</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">                <span class="c1">// 建立 url - RequestMappingInfo的映射关系。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                <span class="c1">// 当一个请求过来的时候，就可以根据url找到对应的RequestMappingInfo，通过RequestMappingInfo
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                <span class="c1">// 就可以在 mappingLookup 中找到 handlerMethod，即controller中的方法。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                <span class="k">this</span><span class="o">.</span><span class="na">urlLookup</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="n">url</span><span class="o">,</span> <span class="n">mapping</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">            <span class="c1">// requestMappingInfo的名称策略，将名称 - requestMappingInfo的映射缓存到 nameLookup。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="n">String</span> <span class="n">name</span> <span class="o">=</span> <span class="kc">null</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span> <span class="o">(</span><span class="n">getNamingStrategy</span><span class="o">()</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">                <span class="n">name</span> <span class="o">=</span> <span class="n">getNamingStrategy</span><span class="o">().</span><span class="na">getName</span><span class="o">(</span><span class="n">handlerMethod</span><span class="o">,</span> <span class="n">mapping</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">                <span class="n">addMappingName</span><span class="o">(</span><span class="n">name</span><span class="o">,</span> <span class="n">handlerMethod</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="o">}</span>
</span></span><span class="line"><span class="cl">            <span class="c1">// 缓存跨域配置信息。将handlerMethod和corsConfig的映射缓存到 corsLookup
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="n">CorsConfiguration</span> <span class="n">corsConfig</span> <span class="o">=</span> <span class="n">initCorsConfiguration</span><span class="o">(</span><span class="n">handler</span><span class="o">,</span> <span class="n">method</span><span class="o">,</span> <span class="n">mapping</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span> <span class="o">(</span><span class="n">corsConfig</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">                <span class="k">this</span><span class="o">.</span><span class="na">corsLookup</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">handlerMethod</span><span class="o">,</span> <span class="n">corsConfig</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">            <span class="o">}</span>
</span></span><span class="line"><span class="cl">            <span class="c1">// RequestMappingInfo - MappingRegistration映射。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="c1">// MappingRegistration 中封装了 RequestMappingInfo、HandlerMethod、directUrls、mappingName信息。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="k">this</span><span class="o">.</span><span class="na">registry</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">mapping</span><span class="o">,</span> <span class="k">new</span> <span class="n">MappingRegistration</span><span class="o">&lt;&gt;(</span><span class="n">mapping</span><span class="o">,</span> <span class="n">handlerMethod</span><span class="o">,</span> <span class="n">directUrls</span><span class="o">,</span> <span class="n">name</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">        <span class="o">}</span>
</span></span><span class="line"><span class="cl">        <span class="k">finally</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">            <span class="k">this</span><span class="o">.</span><span class="na">readWriteLock</span><span class="o">.</span><span class="na">writeLock</span><span class="o">().</span><span class="na">unlock</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">        <span class="o">}</span>
</span></span><span class="line"><span class="cl">    <span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>方法流程：</p>
<ol>
<li>创建 HandlerMethod。</li>
<li>将 RequestMappingInfo - HandlerMethod 的映射关系存储到 mappingLookup。</li>
<li>查找到 RequestMappingInfo 中所有的 url信息。</li>
<li>将 url - RequestMappingInfo 的映射关系，存储到 urlLookup。</li>
<li>初始化跨域相关配置信息，将 HandlerMethod - corsConfig 映射关系存储到 corsLookup。</li>
<li>将 RequestMappingInfo、HandlerMethod、directUrls、mappingName 信息封装到 MappingRegistration，并以 RequestMappingInfo 作为键值，缓存到变量 registry。</li>
</ol>
<p>mappingRegistry 是 RequestMappingHandlerMapping 中的一个成员变量，最终，上面流程获取到的信息都会注册到这里。</p>
<p>它的声明如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">abstract</span> <span class="kd">class</span> <span class="nc">AbstractHandlerMethodMapping</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMapping</span> <span class="kd">implements</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">	<span class="cm">/** 注册mapping，这里面封装了一系列的映射信息，url-requestMappingInfo、requestMappingInfo-handlerMethod等的映射。 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">MappingRegistry</span> <span class="n">mappingRegistry</span> <span class="o">=</span> <span class="k">new</span> <span class="n">MappingRegistry</span><span class="o">();</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>MappingRegistry 的数据结构：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">class</span> <span class="nc">MappingRegistry</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">    <span class="cm">/** 封装了 RequestMappingInfo、HandlerMethod、directUrls、mappingName信息。 */</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="kd">final</span> <span class="n">Map</span><span class="o">&lt;</span><span class="n">T</span><span class="o">,</span> <span class="n">MappingRegistration</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;&gt;</span> <span class="n">registry</span> <span class="o">=</span> <span class="k">new</span> <span class="n">HashMap</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">    <span class="cm">/** 封装 RequestMappingInfo - HandlerMethod 映射关系 */</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="kd">final</span> <span class="n">Map</span><span class="o">&lt;</span><span class="n">T</span><span class="o">,</span> <span class="n">HandlerMethod</span><span class="o">&gt;</span> <span class="n">mappingLookup</span> <span class="o">=</span> <span class="k">new</span> <span class="n">LinkedHashMap</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">    <span class="cm">/** 封装 url - RequestMappingInfo 映射信息 */</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="kd">final</span> <span class="n">MultiValueMap</span><span class="o">&lt;</span><span class="n">String</span><span class="o">,</span> <span class="n">T</span><span class="o">&gt;</span> <span class="n">urlLookup</span> <span class="o">=</span> <span class="k">new</span> <span class="n">LinkedMultiValueMap</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">    <span class="cm">/** 封装 RequestMappingInfo名称 - HandlerMethod列表 映射信息 */</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="kd">final</span> <span class="n">Map</span><span class="o">&lt;</span><span class="n">String</span><span class="o">,</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethod</span><span class="o">&gt;&gt;</span> <span class="n">nameLookup</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ConcurrentHashMap</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">    <span class="cm">/** 封装 handlerMethod - cors跨域配置的映射信息 */</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="kd">final</span> <span class="n">Map</span><span class="o">&lt;</span><span class="n">HandlerMethod</span><span class="o">,</span> <span class="n">CorsConfiguration</span><span class="o">&gt;</span> <span class="n">corsLookup</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ConcurrentHashMap</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">    <span class="cm">/** 读写锁，保证线程安全，在写入的时候不允许读写，读操作可以并行执行 */</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="kd">final</span> <span class="n">ReentrantReadWriteLock</span> <span class="n">readWriteLock</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ReentrantReadWriteLock</span><span class="o">();</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>封装了许多的有关 url、RequestMappingInfo、HandlerMethod、cors配置等的映射关系，以map的方式存储到成员变量中。</p>
<p>HandlerMethod 的构造及数据结构：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">HandlerMethod</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** Logger that is available to subclasses. */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">protected</span> <span class="kd">final</span> <span class="n">Log</span> <span class="n">logger</span> <span class="o">=</span> <span class="n">LogFactory</span><span class="o">.</span><span class="na">getLog</span><span class="o">(</span><span class="n">getClass</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** bean实例 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">Object</span> <span class="n">bean</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** beanFactory 工厂 */</span>
</span></span><span class="line"><span class="cl">	<span class="nd">@Nullable</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">BeanFactory</span> <span class="n">beanFactory</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** bean的类型 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">beanType</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 方法 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">Method</span> <span class="n">method</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 桥接方法 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">Method</span> <span class="n">bridgedMethod</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 方法参数封装 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">MethodParameter</span><span class="o">[]</span> <span class="n">parameters</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="c1">// 省略其他变量...
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>
</span></span><span class="line"><span class="cl">	<span class="kd">public</span> <span class="nf">HandlerMethod</span><span class="o">(</span><span class="n">String</span> <span class="n">beanName</span><span class="o">,</span> <span class="n">BeanFactory</span> <span class="n">beanFactory</span><span class="o">,</span> <span class="n">Method</span> <span class="n">method</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">	    <span class="c1">// 省略无关代码...
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="c1">// 这里的变量 bean，仅仅封装了一个 beanName，并没有设置具体的实例。这个实例会在第一次调用controller方法时，去设置。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">this</span><span class="o">.</span><span class="na">bean</span> <span class="o">=</span> <span class="n">beanName</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">		<span class="k">this</span><span class="o">.</span><span class="na">beanFactory</span> <span class="o">=</span> <span class="n">beanFactory</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">		<span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">beanType</span> <span class="o">=</span> <span class="n">beanFactory</span><span class="o">.</span><span class="na">getType</span><span class="o">(</span><span class="n">beanName</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="n">beanType</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">&#34;Cannot resolve bean type for bean with name &#39;&#34;</span> <span class="o">+</span> <span class="n">beanName</span> <span class="o">+</span> <span class="s">&#34;&#39;&#34;</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 这里仅仅设置了一个beanType，这时候，bean实例并没有封装进来。在真正调用方法执行时，这个bean实例是必须有的。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="c1">// 它在别的地方进行了设置。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">this</span><span class="o">.</span><span class="na">beanType</span> <span class="o">=</span> <span class="n">ClassUtils</span><span class="o">.</span><span class="na">getUserClass</span><span class="o">(</span><span class="n">beanType</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="k">this</span><span class="o">.</span><span class="na">method</span> <span class="o">=</span> <span class="n">method</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">		<span class="k">this</span><span class="o">.</span><span class="na">bridgedMethod</span> <span class="o">=</span> <span class="n">BridgeMethodResolver</span><span class="o">.</span><span class="na">findBridgedMethod</span><span class="o">(</span><span class="n">method</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="k">this</span><span class="o">.</span><span class="na">parameters</span> <span class="o">=</span> <span class="n">initMethodParameters</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">		<span class="n">evaluateResponseStatus</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>注意这里的变量 this.bean 保存的是 beanName，而非 bean 的实例。</p>
<p>在构造 HandlerMethod 时，仅仅把 beanName 和 beanClass 设置到成员变量保存起来，在这里并没有获取 bean 的具体实例，这个实例实际上是在第一次调用的时候，通过 beanFactory.getBean() 获取的，获取后，将 this.bean 的值替换为了具体的实例。这也是懒加载的一种体现。</p>
<h2 id="2-requestmappinghandleradapter-的初始化">2 RequestMappingHandlerAdapter 的初始化</h2>
<h3 id="21-数据结构">2.1 数据结构</h3>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">RequestMappingHandlerAdapter</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMethodAdapter</span>
</span></span><span class="line"><span class="cl">		<span class="kd">implements</span> <span class="n">BeanFactoryAware</span><span class="o">,</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">	
</span></span><span class="line"><span class="cl">	<span class="kd">public</span> <span class="kd">static</span> <span class="kd">final</span> <span class="n">MethodFilter</span> <span class="n">INIT_BINDER_METHODS</span> <span class="o">=</span> <span class="n">method</span> <span class="o">-&gt;</span>
</span></span><span class="line"><span class="cl">			<span class="n">AnnotatedElementUtils</span><span class="o">.</span><span class="na">hasAnnotation</span><span class="o">(</span><span class="n">method</span><span class="o">,</span> <span class="n">InitBinder</span><span class="o">.</span><span class="na">class</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">	<span class="kd">public</span> <span class="kd">static</span> <span class="kd">final</span> <span class="n">MethodFilter</span> <span class="n">MODEL_ATTRIBUTE_METHODS</span> <span class="o">=</span> <span class="n">method</span> <span class="o">-&gt;</span>
</span></span><span class="line"><span class="cl">			<span class="o">(!</span><span class="n">AnnotatedElementUtils</span><span class="o">.</span><span class="na">hasAnnotation</span><span class="o">(</span><span class="n">method</span><span class="o">,</span> <span class="n">RequestMapping</span><span class="o">.</span><span class="na">class</span><span class="o">)</span> <span class="o">&amp;&amp;</span>
</span></span><span class="line"><span class="cl">					<span class="n">AnnotatedElementUtils</span><span class="o">.</span><span class="na">hasAnnotation</span><span class="o">(</span><span class="n">method</span><span class="o">,</span> <span class="n">ModelAttribute</span><span class="o">.</span><span class="na">class</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">	<span class="cm">/** 自定义的参数解析器，策略模式的运用， HandlerMethodArgumentResolver中提供了两个方法：是否支持解析参数的判断、解析参数方法。*/</span>
</span></span><span class="line"><span class="cl">	<span class="nd">@Nullable</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodArgumentResolver</span><span class="o">&gt;</span> <span class="n">customArgumentResolvers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 参数解析聚合，内部封装了所有的HandlerMethodArgumentResolver实例 */</span>
</span></span><span class="line"><span class="cl">	<span class="nd">@Nullable</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">HandlerMethodArgumentResolverComposite</span> <span class="n">argumentResolvers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** initBinder参数解析器 */</span>
</span></span><span class="line"><span class="cl">	<span class="nd">@Nullable</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">HandlerMethodArgumentResolverComposite</span> <span class="n">initBinderArgumentResolvers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 自定义的返回值处理器 */</span>
</span></span><span class="line"><span class="cl">	<span class="nd">@Nullable</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodReturnValueHandler</span><span class="o">&gt;</span> <span class="n">customReturnValueHandlers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 返回值处理组合，与WebMvcConfigurer组合类设计模式相同。内部封装了所有的HandlerMethodReturnValueHandler */</span>
</span></span><span class="line"><span class="cl">	<span class="nd">@Nullable</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">HandlerMethodReturnValueHandlerComposite</span> <span class="n">returnValueHandlers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 视图解析器 */</span>
</span></span><span class="line"><span class="cl">	<span class="nd">@Nullable</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">ModelAndViewResolver</span><span class="o">&gt;</span> <span class="n">modelAndViewResolvers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">ContentNegotiationManager</span> <span class="n">contentNegotiationManager</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ContentNegotiationManager</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 消息转换器 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">HttpMessageConverter</span><span class="o">&lt;?&gt;&gt;</span> <span class="n">messageConverters</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 一些增强类，参数解析、返回值处理类的封装 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">Object</span><span class="o">&gt;</span> <span class="n">requestResponseBodyAdvice</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ArrayList</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">    <span class="c1">// 省略其他变量...
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>RequestMappingHandlerAdapter 封装了许多的策略处理，包括 方法参数解析、返回值处理、消息转换器等等。每一种都包含许多的方式去处理，有太多可能情况，所以使用策略模式。</p>
<p>无论是 参数解析、返回值、消息转换都有很多种可能，比如 post表单提交的参数、以流的方式传递的 json 参数，等等。每一种都对应的有相应的处理实现类。</p>
<h3 id="22-主流程">2.2 主流程</h3>
<p>首先会调用初始化方法 afterPropertiesSet()，源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">RequestMappingHandlerAdapter</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMethodAdapter</span>
</span></span><span class="line"><span class="cl">		<span class="kd">implements</span> <span class="n">BeanFactoryAware</span><span class="o">,</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">	<span class="kd">public</span> <span class="kt">void</span> <span class="nf">afterPropertiesSet</span><span class="o">()</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// TODO 在第一次执行时，会初始化ControllerAdvice缓存。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="c1">// Do this first, it may add ResponseBody advice beans
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">initControllerAdviceCache</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="k">this</span><span class="o">.</span><span class="na">argumentResolvers</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// TODO 参数解析器，里面注册了很多的参数解析类。实际上，参数的解析是一个十分复杂的过程，它的可能情况太多了。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodArgumentResolver</span><span class="o">&gt;</span> <span class="n">resolvers</span> <span class="o">=</span> <span class="n">getDefaultArgumentResolvers</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// 将所有的参数解析器封装到 argumentResolvers 中。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="k">this</span><span class="o">.</span><span class="na">argumentResolvers</span> <span class="o">=</span> <span class="k">new</span> <span class="n">HandlerMethodArgumentResolverComposite</span><span class="o">().</span><span class="na">addResolvers</span><span class="o">(</span><span class="n">resolvers</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="k">this</span><span class="o">.</span><span class="na">initBinderArgumentResolvers</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// initBinder 参数解析器
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodArgumentResolver</span><span class="o">&gt;</span> <span class="n">resolvers</span> <span class="o">=</span> <span class="n">getDefaultInitBinderArgumentResolvers</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">			<span class="k">this</span><span class="o">.</span><span class="na">initBinderArgumentResolvers</span> <span class="o">=</span> <span class="k">new</span> <span class="n">HandlerMethodArgumentResolverComposite</span><span class="o">().</span><span class="na">addResolvers</span><span class="o">(</span><span class="n">resolvers</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="k">this</span><span class="o">.</span><span class="na">returnValueHandlers</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// 方法返回值处理类注册
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodReturnValueHandler</span><span class="o">&gt;</span> <span class="n">handlers</span> <span class="o">=</span> <span class="n">getDefaultReturnValueHandlers</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">			<span class="k">this</span><span class="o">.</span><span class="na">returnValueHandlers</span> <span class="o">=</span> <span class="k">new</span> <span class="n">HandlerMethodReturnValueHandlerComposite</span><span class="o">().</span><span class="na">addHandlers</span><span class="o">(</span><span class="n">handlers</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><ol>
<li>首先缓存异常处理相关类。</li>
<li>注册默认的参数解析器设置。这里会注册一系列的参数解析器。</li>
<li>注册 initBinder 参数解析器。同上。</li>
<li>注册默认的方法返回值处理类。同上。</li>
</ol>
<h3 id="23-初始化-controlleradvice-缓存">2.3 初始化 ControllerAdvice 缓存</h3>
<p>源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">RequestMappingHandlerAdapter</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMethodAdapter</span>
</span></span><span class="line"><span class="cl">		<span class="kd">implements</span> <span class="n">BeanFactoryAware</span><span class="o">,</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kt">void</span> <span class="nf">initControllerAdviceCache</span><span class="o">()</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(</span><span class="n">getApplicationContext</span><span class="o">()</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="k">return</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// TODO 全局异常处理的Bean扫描，@ControllerAdvice 注解的bean会被扫描到。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">List</span><span class="o">&lt;</span><span class="n">ControllerAdviceBean</span><span class="o">&gt;</span> <span class="n">adviceBeans</span> <span class="o">=</span> <span class="n">ControllerAdviceBean</span><span class="o">.</span><span class="na">findAnnotatedBeans</span><span class="o">(</span><span class="n">getApplicationContext</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">AnnotationAwareOrderComparator</span><span class="o">.</span><span class="na">sort</span><span class="o">(</span><span class="n">adviceBeans</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="n">List</span><span class="o">&lt;</span><span class="n">Object</span><span class="o">&gt;</span> <span class="n">requestResponseBodyAdviceBeans</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ArrayList</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">for</span> <span class="o">(</span><span class="n">ControllerAdviceBean</span> <span class="n">adviceBean</span> <span class="o">:</span> <span class="n">adviceBeans</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">Class</span><span class="o">&lt;?&gt;</span> <span class="n">beanType</span> <span class="o">=</span> <span class="n">adviceBean</span><span class="o">.</span><span class="na">getBeanType</span><span class="o">();</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(</span><span class="n">beanType</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">&#34;Unresolvable type for ControllerAdviceBean: &#34;</span> <span class="o">+</span> <span class="n">adviceBean</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// 方法过滤器 @RequestMapping &amp;&amp; @ModelAttribute 注解扫描
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">Set</span><span class="o">&lt;</span><span class="n">Method</span><span class="o">&gt;</span> <span class="n">attrMethods</span> <span class="o">=</span> <span class="n">MethodIntrospector</span><span class="o">.</span><span class="na">selectMethods</span><span class="o">(</span><span class="n">beanType</span><span class="o">,</span> <span class="n">MODEL_ATTRIBUTE_METHODS</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(!</span><span class="n">attrMethods</span><span class="o">.</span><span class="na">isEmpty</span><span class="o">())</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="c1">// 封装adviceBean和 @ModelAttribute 注解方法的映射关系。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="k">this</span><span class="o">.</span><span class="na">modelAttributeAdviceCache</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">adviceBean</span><span class="o">,</span> <span class="n">attrMethods</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">			<span class="c1">// 方法过滤器 InitBinder 扫描
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">Set</span><span class="o">&lt;</span><span class="n">Method</span><span class="o">&gt;</span> <span class="n">binderMethods</span> <span class="o">=</span> <span class="n">MethodIntrospector</span><span class="o">.</span><span class="na">selectMethods</span><span class="o">(</span><span class="n">beanType</span><span class="o">,</span> <span class="n">INIT_BINDER_METHODS</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(!</span><span class="n">binderMethods</span><span class="o">.</span><span class="na">isEmpty</span><span class="o">())</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="c1">// 封装 adviceBean 和 binderMethods 的映射关系
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="k">this</span><span class="o">.</span><span class="na">initBinderAdviceCache</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">adviceBean</span><span class="o">,</span> <span class="n">binderMethods</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(</span><span class="n">RequestBodyAdvice</span><span class="o">.</span><span class="na">class</span><span class="o">.</span><span class="na">isAssignableFrom</span><span class="o">(</span><span class="n">beanType</span><span class="o">))</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="n">requestResponseBodyAdviceBeans</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="n">adviceBean</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="o">(</span><span class="n">ResponseBodyAdvice</span><span class="o">.</span><span class="na">class</span><span class="o">.</span><span class="na">isAssignableFrom</span><span class="o">(</span><span class="n">beanType</span><span class="o">))</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">				<span class="n">requestResponseBodyAdviceBeans</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="n">adviceBean</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">			<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="o">(!</span><span class="n">requestResponseBodyAdviceBeans</span><span class="o">.</span><span class="na">isEmpty</span><span class="o">())</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="k">this</span><span class="o">.</span><span class="na">requestResponseBodyAdvice</span><span class="o">.</span><span class="na">addAll</span><span class="o">(</span><span class="n">0</span><span class="o">,</span> <span class="n">requestResponseBodyAdviceBeans</span><span class="o">);</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 省略无关代码...
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>这里重点在注解扫描，源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">ControllerAdviceBean</span> <span class="kd">implements</span> <span class="n">Ordered</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">    <span class="kd">public</span> <span class="kd">static</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">ControllerAdviceBean</span><span class="o">&gt;</span> <span class="nf">findAnnotatedBeans</span><span class="o">(</span><span class="n">ApplicationContext</span> <span class="n">context</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 这里是针对Controller层全局异常处理注解支持的扫描。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">return</span> <span class="n">Arrays</span><span class="o">.</span><span class="na">stream</span><span class="o">(</span><span class="n">BeanFactoryUtils</span><span class="o">.</span><span class="na">beanNamesForTypeIncludingAncestors</span><span class="o">(</span><span class="n">context</span><span class="o">,</span> <span class="n">Object</span><span class="o">.</span><span class="na">class</span><span class="o">))</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">filter</span><span class="o">(</span><span class="n">name</span> <span class="o">-&gt;</span> <span class="n">context</span><span class="o">.</span><span class="na">findAnnotationOnBean</span><span class="o">(</span><span class="n">name</span><span class="o">,</span> <span class="n">ControllerAdvice</span><span class="o">.</span><span class="na">class</span><span class="o">)</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">map</span><span class="o">(</span><span class="n">name</span> <span class="o">-&gt;</span> <span class="k">new</span> <span class="n">ControllerAdviceBean</span><span class="o">(</span><span class="n">name</span><span class="o">,</span> <span class="n">context</span><span class="o">))</span>
</span></span><span class="line"><span class="cl">				<span class="o">.</span><span class="na">collect</span><span class="o">(</span><span class="n">Collectors</span><span class="o">.</span><span class="na">toList</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>上面流程中，扫描了容器中所有带有 @ControllerAdvice 注解的 beanName，并封装为 ControllerAdviceBean。ControllerAdviceBean 中封装了 bean实例（刚开始是beanName）、排序、@ControllerAdvice注解信息。</p>
<p>ControllerAdviceBean 数据结构如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">ControllerAdviceBean</span> <span class="kd">implements</span> <span class="n">Ordered</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** bean实例 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">Object</span> <span class="n">bean</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** beanFactory */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">BeanFactory</span> <span class="n">beanFactory</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** 排序，通过@Order注解来设置 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="kt">int</span> <span class="n">order</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="cm">/** ControllerAdvice 注解中的参数信息封装 */</span>
</span></span><span class="line"><span class="cl">	<span class="kd">private</span> <span class="kd">final</span> <span class="n">HandlerTypePredicate</span> <span class="n">beanTypePredicate</span><span class="o">;</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><h3 id="24-注册默认参数解析器">2.4 注册默认参数解析器</h3>
<p>getDefaultArgumentResolvers() 源码如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">RequestMappingHandlerAdapter</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMethodAdapter</span>
</span></span><span class="line"><span class="cl">		<span class="kd">implements</span> <span class="n">BeanFactoryAware</span><span class="o">,</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodArgumentResolver</span><span class="o">&gt;</span> <span class="nf">getDefaultArgumentResolvers</span><span class="o">()</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodArgumentResolver</span><span class="o">&gt;</span> <span class="n">resolvers</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ArrayList</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 这里注册了一系列的默认参数解析器，在大多数应用场景下的参数解析，都是可以支持的，一般不需要我们自定义。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="c1">// Annotation-based argument resolution
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestParamMethodArgumentResolver</span><span class="o">(</span><span class="n">getBeanFactory</span><span class="o">(),</span> <span class="kc">false</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestParamMapMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">PathVariableMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">PathVariableMapMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">MatrixVariableMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">MatrixVariableMapMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ServletModelAttributeMethodProcessor</span><span class="o">(</span><span class="kc">false</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestResponseBodyMethodProcessor</span><span class="o">(</span><span class="n">getMessageConverters</span><span class="o">(),</span> <span class="k">this</span><span class="o">.</span><span class="na">requestResponseBodyAdvice</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestPartMethodArgumentResolver</span><span class="o">(</span><span class="n">getMessageConverters</span><span class="o">(),</span> <span class="k">this</span><span class="o">.</span><span class="na">requestResponseBodyAdvice</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestHeaderMethodArgumentResolver</span><span class="o">(</span><span class="n">getBeanFactory</span><span class="o">()));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestHeaderMapMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ServletCookieValueMethodArgumentResolver</span><span class="o">(</span><span class="n">getBeanFactory</span><span class="o">()));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ExpressionValueMethodArgumentResolver</span><span class="o">(</span><span class="n">getBeanFactory</span><span class="o">()));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">SessionAttributeMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestAttributeMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">// Type-based argument resolution
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ServletRequestMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ServletResponseMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">HttpEntityMethodProcessor</span><span class="o">(</span><span class="n">getMessageConverters</span><span class="o">(),</span> <span class="k">this</span><span class="o">.</span><span class="na">requestResponseBodyAdvice</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RedirectAttributesMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ModelMethodProcessor</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">MapMethodProcessor</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ErrorsMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">SessionStatusMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">UriComponentsBuilderMethodArgumentResolver</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">// Custom arguments
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">if</span> <span class="o">(</span><span class="n">getCustomArgumentResolvers</span><span class="o">()</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">resolvers</span><span class="o">.</span><span class="na">addAll</span><span class="o">(</span><span class="n">getCustomArgumentResolvers</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">// Catch-all
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestParamMethodArgumentResolver</span><span class="o">(</span><span class="n">getBeanFactory</span><span class="o">(),</span> <span class="kc">true</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">resolvers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ServletModelAttributeMethodProcessor</span><span class="o">(</span><span class="kc">true</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">return</span> <span class="n">resolvers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>注册了许多的参数解析器，实际上，参数的解析十分复杂。</p>
<p>从类名称上大致可以推断出它的作用。</p>
<p>比如 PathVariableMethodArgumentResolver 就是处理 url 中使用占位符接收参数。RequestParamMethodArgumentResolver 处理表单提交的参数。RequestResponseBodyMethodProcessor 处理json参数等。</p>
<h3 id="25-注册默认返回值处理类">2.5 注册默认返回值处理类</h3>
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<pre tabindex="0" class="chroma"><code class="language-java" data-lang="java"><span class="line"><span class="cl"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">RequestMappingHandlerAdapter</span> <span class="kd">extends</span> <span class="n">AbstractHandlerMethodAdapter</span>
</span></span><span class="line"><span class="cl">		<span class="kd">implements</span> <span class="n">BeanFactoryAware</span><span class="o">,</span> <span class="n">InitializingBean</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">    <span class="kd">private</span> <span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodReturnValueHandler</span><span class="o">&gt;</span> <span class="nf">getDefaultReturnValueHandlers</span><span class="o">()</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">		<span class="n">List</span><span class="o">&lt;</span><span class="n">HandlerMethodReturnValueHandler</span><span class="o">&gt;</span> <span class="n">handlers</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ArrayList</span><span class="o">&lt;&gt;();</span>
</span></span><span class="line"><span class="cl">		<span class="c1">// 注册了很多返回值处理类，用于处理返回值的一些信息。
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="c1">// Single-purpose return value types
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ModelAndViewMethodReturnValueHandler</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ModelMethodProcessor</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ViewMethodReturnValueHandler</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ResponseBodyEmitterReturnValueHandler</span><span class="o">(</span><span class="n">getMessageConverters</span><span class="o">(),</span>
</span></span><span class="line"><span class="cl">				<span class="k">this</span><span class="o">.</span><span class="na">reactiveAdapterRegistry</span><span class="o">,</span> <span class="k">this</span><span class="o">.</span><span class="na">taskExecutor</span><span class="o">,</span> <span class="k">this</span><span class="o">.</span><span class="na">contentNegotiationManager</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">StreamingResponseBodyReturnValueHandler</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">HttpEntityMethodProcessor</span><span class="o">(</span><span class="n">getMessageConverters</span><span class="o">(),</span>
</span></span><span class="line"><span class="cl">				<span class="k">this</span><span class="o">.</span><span class="na">contentNegotiationManager</span><span class="o">,</span> <span class="k">this</span><span class="o">.</span><span class="na">requestResponseBodyAdvice</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">HttpHeadersReturnValueHandler</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">CallableMethodReturnValueHandler</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">DeferredResultMethodReturnValueHandler</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">AsyncTaskMethodReturnValueHandler</span><span class="o">(</span><span class="k">this</span><span class="o">.</span><span class="na">beanFactory</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">// Annotation-based return value types
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ModelAttributeMethodProcessor</span><span class="o">(</span><span class="kc">false</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">RequestResponseBodyMethodProcessor</span><span class="o">(</span><span class="n">getMessageConverters</span><span class="o">(),</span>
</span></span><span class="line"><span class="cl">				<span class="k">this</span><span class="o">.</span><span class="na">contentNegotiationManager</span><span class="o">,</span> <span class="k">this</span><span class="o">.</span><span class="na">requestResponseBodyAdvice</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">// Multi-purpose return value types
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ViewNameMethodReturnValueHandler</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">MapMethodProcessor</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">// Custom return value types
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">if</span> <span class="o">(</span><span class="n">getCustomReturnValueHandlers</span><span class="o">()</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">handlers</span><span class="o">.</span><span class="na">addAll</span><span class="o">(</span><span class="n">getCustomReturnValueHandlers</span><span class="o">());</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">// Catch-all
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">if</span> <span class="o">(!</span><span class="n">CollectionUtils</span><span class="o">.</span><span class="na">isEmpty</span><span class="o">(</span><span class="n">getModelAndViewResolvers</span><span class="o">()))</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ModelAndViewResolverMethodReturnValueHandler</span><span class="o">(</span><span class="n">getModelAndViewResolvers</span><span class="o">()));</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">		<span class="k">else</span> <span class="o">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">handlers</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="k">new</span> <span class="n">ModelAttributeMethodProcessor</span><span class="o">(</span><span class="kc">true</span><span class="o">));</span>
</span></span><span class="line"><span class="cl">		<span class="o">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="k">return</span> <span class="n">handlers</span><span class="o">;</span>
</span></span><span class="line"><span class="cl">	<span class="o">}</span>
</span></span><span class="line"><span class="cl"><span class="o">}</span>
</span></span></code></pre></td></tr></table>
</div>
</div><p>如上源码，返回值的处理类也有很多。</p>
<p>其他的一些策略类的注册，与上面流程类似。</p></div>

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